ISMEAR: Difference between revisions

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== Tag options ==
== Tag options ==


*{{TAGO|ISMEAR|0|op=>}}: method of Methfessel-Paxton order {{TAG|ISMEAR}} with width {{TAG|SIGMA}}.
*{{TAG|ISMEAR|0|op=>}}: method of Methfessel-Paxton order {{TAG|ISMEAR}} with width {{TAG|SIGMA}}.
{{NB|mind|Methfessel-Paxton can yield erroneous results for insulators because the partial occupancies can be unphysical.|:}}
{{NB|mind|Methfessel-Paxton can yield erroneous results for insulators because the partial occupancies can be unphysical.|:}}


*{{TAGO|ISMEAR|0}}: Gaussian smearing with width {{TAG|SIGMA}}.
*{{TAG|ISMEAR|0}}: Gaussian smearing with width {{TAG|SIGMA}}.


*{{TAGO|ISMEAR|-1}}: Fermi smearing with width {{TAG|SIGMA}}.
*{{TAG|ISMEAR|-1}}: Fermi smearing with width {{TAG|SIGMA}}.


*{{TAGO|ISMEAR|-2}}: Partial occupancies are read in from the {{FILE|WAVECAR}} and kept fixed throughout run. Alternatively, you can also choose occupancies in the {{FILE|INCAR}} file with the tag {{TAG|FERWE}} (and {{TAG|FERDO}} for {{TAGO|ISPIN|2}} calculations).
*{{TAG|ISMEAR|-2}}: Partial occupancies are read in from the {{FILE|WAVECAR}} and kept fixed throughout run. Alternatively, you can also choose occupancies in the {{FILE|INCAR}} file with the tag {{TAG|FERWE}} (and {{TAG|FERDO}} for {{TAG|ISPIN|2}} calculations).


*{{TAGO|ISMEAR|-3}}: perform a loop over {{TAG|SMEARINGS}} parameters supplied in the {{FILE|INCAR}} file.
*{{TAG|ISMEAR|-3}}: perform a loop over {{TAG|SMEARINGS}} parameters supplied in the {{FILE|INCAR}} file.


*{{TAGO|ISMEAR|-4}}: Tetrahedron method without smearing.
*{{TAG|ISMEAR|-4}}: Tetrahedron method without smearing.


*{{TAGO|ISMEAR|-5}}: Tetrahedron method with Blöchl corrections without smearing.
*{{TAG|ISMEAR|-5}}: Tetrahedron method with Blöchl corrections without smearing.


*{{TAGO|ISMEAR|-14}}: Tetrahedron method with Fermi-Dirac smearing {{TAG|SIGMA}}.
*{{TAG|ISMEAR|-14}}: Tetrahedron method with Fermi-Dirac smearing {{TAG|SIGMA}}.


*{{TAGO|ISMEAR|-15}}: Tetrahedron method with Blöchl corrections with Fermi-Dirac smearing {{TAG|SIGMA}}.
*{{TAG|ISMEAR|-15}}: Tetrahedron method with Blöchl corrections with Fermi-Dirac smearing {{TAG|SIGMA}}.
{{NB|mind|Use a [[KPOINTS|Γ-centered '''k'''-mesh]] for the tetrahedron methods.|:}}
{{NB|mind|Use a [[KPOINTS|Γ-centered '''k'''-mesh]] for the tetrahedron methods.|:}}


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{{TAG|SMEARINGS}},
{{TAG|SMEARINGS}},
[[Smearing technique]],
[[Smearing technique]],
[[K-point integration]],
[[K-point integration]]
[[Chemical potential]]


{{sc|ISMEAR|Examples|Examples that use this tag}}
{{sc|ISMEAR|Examples|Examples that use this tag}}

Latest revision as of 07:45, 24 October 2025

ISMEAR = -15 | -14 | -5 | -4 | -3 | -2 | -1 | 0 | [integer]>0
Default: ISMEAR = 1 

Description: ISMEAR determines how the partial occupancies fnk are set for each orbital. SIGMA determines the width of the smearing in eV.

Please consider how-to guide to choose the optimal smearing technique.

Tag options

Mind: Methfessel-Paxton can yield erroneous results for insulators because the partial occupancies can be unphysical.
  • ISMEAR = -2: Partial occupancies are read in from the WAVECAR and kept fixed throughout run. Alternatively, you can also choose occupancies in the INCAR file with the tag FERWE (and FERDO for ISPIN = 2 calculations).
  • ISMEAR = -4: Tetrahedron method without smearing.
  • ISMEAR = -5: Tetrahedron method with Blöchl corrections without smearing.
  • ISMEAR = -14: Tetrahedron method with Fermi-Dirac smearing SIGMA.
  • ISMEAR = -15: Tetrahedron method with Blöchl corrections with Fermi-Dirac smearing SIGMA.
Mind: Use a Γ-centered k-mesh for the tetrahedron methods.

Related tags and articles

SIGMA, EFERMI, FERWE, FERDO, SMEARINGS, Smearing technique, K-point integration

Examples that use this tag

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